A fiber optic strain gauge is typically attached to a host structure to measure the strain of or vibration experienced by the host structure. The strain or vibration of the host structure is transferred to the fiber Bragg grating (FBG) attached to a profiled or etched metal mount. FBGs are structures recorded within a core of an optical fiber. The structure of an FBG causes light of a specific wavelength, known as the Bragg wavelength, to be reflected within the fiber. Both the pitch (Λ) and effective refractive index (neff) of the structure and consequently, the Bragg wavelength (given by 2neffΛ), are sensitive to strain and temperature in a highly repetitive manner. Therefore, a FBG is an excellent fiber optic sensor. The strain or temperature of the FBG is encoded in the Bragg wavelength which may be measured using an optical interrogator.
An accurate strain gauge that is also reliable is highly desirable.